The steam train will put out steam, which here in reality is white, and the diesel trains again, remember this is based on reality, put out black fumes.
This is a hugely amusing thread which has wasted hours of my time this morning. Haven’t read it all so this may have been pointed out before. The white stuff coming out of a steam train’s funnel is not steam. It is the product of the combustion of the coal which is heating the water to produce the steam. It is smoke; just as villainous as deisel fumes.. That is why, as I remember from my childhood, it is smelly and smutty.
In theory there shouldn’t be any steam coming from a steam engine as it is the steam, under pressure in a closed system, that is providing the motive power. If the steam were escaping the engine wouldn’t move.
OK, (sorry, ok,) as you were with the humour please..
Pedantry worthy of STW 🙂